Compared with conventional steel reinforced concrete column, concrete-filled steel tubular column has advantages such as saving template, high construction speed and high carrying capacity, and has been widely used in the field of civil engineering and construction at home and abroad. However, a large number of experiments found that, axial compressive failure of the concrete-filled steel tubular column is mainly manifested as waist bloating shape failure mode that it is seriously bloated close to a half high of a column shaft, while transverse deformation of upper and lower ends of the column shaft is less obvious. At this time, steel materials at the upper and lower ends of the column shaft have not actually gotten into full play to the role of horizontal restraint. Therefore, in the case of amount of steel remains the same, the concrete-filled steel tubular column may be further optimized by adjusting material layout (i.e. increasing the proportion of steel consumed close to the half high of the column shaft, while decreasing the proportion of steel consumed to the upper and lower ends of the column shaft), and thereby its axial compression performance is improved, but such technology is rarely seen by now.
Since natural sand and gravel mining destroys the environment, and directly transporting waste concrete produced by demolishing existing buildings and structures towards a suburb for stacking or burying will lead to a new environment problem, recycle use of the waste concrete has attracted more and more attention at home and abroad. In general, since the construction of waste concrete is earlier, and strength grade is generally low, in the past the waste concrete was only used with fresh concrete with close strength grade, with range of application being subjected to great restraints (for example, cannot be directly applied to high-level, heavy load and other structures), so how to effectively expand the range of application of normal-strength demolished concrete is an urgent problem to be solved.
To sum up, problems exist in the prior arts, such as material layout of the axial compression concrete-filled steel tubular column being not reasonable enough and the range of application of the normal-strength demolished concrete being urgent to expand.